The overall weight can't exceed 1,918 pounds, which is 66 pounds lighter than last year's racers.

The shape of the 919 has undergone 2,000 hours of wind tunnel testing.

The entire body is made of carbon fiber, along with the monocoque, similar to those used in F1.

Two energy recovery systems juice up the battery.

Energy is stored in a water-cooled lithium-ion battery pack, and sends power to the front wheels.

The engine is an odd one. A turbocharged 2.0-liter V4--yes, V4--puts out over 500 hp at 9,000 rpm.

Just for a sense of scale, the 919 is tiny in comparison to Porsche's new 911 GT3 race car.

If you can't make out what that says, it's "Porsche Intelligent Perfomance"

The future of racing is about more than speed. It's about using technology to combine performance and efficiency in a winning package. Nowhere is this more important that at Le Mans, where Porsche hopes the 919 Hybrid will redefine endurance racing.

Porsche is returning to the greatest race in the world after a 16 year hiatus to compete in the top-tier prototype class. Although private teams have raced, and won, at Le Mans in various iterations of the venerable Porsche 911, the automaker has not fielded a factory team since the GT1 took the overall win in 1998.

Porsche timed its return to exploit new World Endurance Championship regulations to make racing more efficient, in every way. That means smaller engines, hybrid drivetrains and wider use of lightweight materials. The company, which has pioneered a wide range of motorsports technology that eventually wound up on road cars, calls the 919 "the most technologically advanced race car Porsche has produced." The machine builds on the lessons learned from the 911 GT3 R Hybrid race car and the 918 gas-electric supercar and applies them to the most grueling race in the world.

It's entering an arena dominated by Audi. Although Porsche has racked up 16 outright wins at Le Mans–more than any other manufacturer–Audi is the team to beat. It's amassed 12 wins in 14 years with its diesel racers, but has faced stiff competition from hybrid racers from Peugeot and Toyota in the past.

Like Porsche, Audi and Toyota are bringing hybrids to Circuit de Le Sarthe in June, but Porsche has the most at stake. It has more than a racing rep to uphold, it has a technological one as well. Ferdinand Porsche developed the world's first hybrid car over 110 years ago. Even if Porsche purists may not want to admit it, gas-electric technology is a hallmark of the marque. And that heritage is going to come into play in a big way.

The LMP1-H class of prototype racers in which Audi, Porsche, and Toyota are competing must, under the rules, carry less fuel–and therefore burn less fuel–than in the past. At the bottom line, they've got about 30 percent less fuel per lap to play with than last year. To offset that, the amount of energy they can carry in batteries or hybrid flywheel systems has increased substantially. But naturally, there are restrictions. And here's where it gets a bit tricky.

Depending on the type of drivetrain used, a car can use two, four, six, or eight megajoules per lap at Le Mans. Exceed that and they'll be held in the pits for between 10 and 60 seconds–a lifetime in a race where minutes, or even seconds, can separate first and second place.

While Audi is using a diesel V6 and Toyota is running a gas V8, Porsche is a 2.0-liter V4–yes, V4–producing close to 500 horsepower and spinning at 9,000 rpm. Of course it's got direct injection and turbocharging, but that's not especially noteworthy considering you can find that in a Ford Focus.

What's most impressive about the 919 is the two ways Porsche recovers energy to juice up its hybrid system. The first system uses an electric generator with a turbine driven by the exhaust. A second system gathers kinetic energy during braking just like a Toyota Prius. All that energy is stored in a water-cooled, lithium-ion battery pack (Porsche isn't saying how big it is) that powers an electric motor (Porsche won't say how powerful) that drives the front wheels, giving the 919 on-demand all wheel drive.

Porsche is competing in the Premiere Class, which gives it the maximum eight megajoules to play with. Although that means the hybrid system is heavier and more complex–which means there are more things that can go wrong–it also means less fuel consumption. Greater efficiency means less time spent refueling, which means greater distance covered, and that's the entire point of endurance racing. Porsche says the 919's engine will be driven at full load 75 percent of the 8.48-mile circuit, and use just 1.23 gallons of fuel in the process. Drivers adjust, on the fly, when and how the electric boost comes on, allowing them to account for, say, track conditions or a dogfight in traffic.

Despite all this hardware, the 919 Hybrid is remarkably light at 1,918 pounds–66 pounds lighter than last year's cars. You can do that when you use carbon fiber for pretty much everything, from the bodywork to the tub the driver sits in. The car is tiny, too, just 183.1 inches long, about 70 inches wide, and just 41.3 inches tall–nearly waist-height. It makes the 911, which is by no means a leviathan, look absolutely huge.

The 919's first battle is set to take place on April 20th at Silverstone, with the 24 Hours of Le Mans in June and another seven, six-hour races throughout the season.1

But don't think all this tech is just for the track. Porsche has a storied history of bringing race technology to the road. The list includes the stuff already on your car, like fuel injection and disc brakes, and more specialized fare like dual clutch transmissions and even carbon fiber monocoque construction. Bet on Porsche using the 919 to expand that tradition. Porsche says the 919 is a research and development platform for for future models. It's already begun with the 918 Spyder. It's only a matter of time before you see you see this technology in the 911.

1 CORRECTION 1:13 PM Eastern 03/07/14: An earlier version of this story incorrectly stated the WEC race calendar.